How to repeat code in java

Question

So for a school project I'm doing, I am copying the same code and pasting it, just changing the Identifier name.

if (s1.isSelected()){
        System.out.println("Hello");
    String query = "update booking set s1 = 0 where bdate ='"+d+"';";
    stmt.executeUpdate(query);
    }

if (s2.isSelected()){
        System.out.println("Hello");
    String query = "update booking set s2 = 0 where bdate ='"+d+"';";
    stmt.executeUpdate(query);
    }
if (s3.isSelected()){
        System.out.println("Hello");
    String query = "update booking set s3 = 0 where bdate ='"+d+"';";
    stmt.executeUpdate(query);
    }

How do I repeat this code for 100-120 times? Is there an easy way of doing this?

Thanks.

Answer 1

Read about

void putClientProperty(Object key, Object value);

and

Object getClientProperty(Object key);

Almost every GUI system, binary Win32 too, has similar concept to store specific data with/in component. This drastically eliminate stupid repeatable code, strange if s series etc. For example

List<JCheckBox> boxes = ... ;

for(...){
    JCheckBox box = ... // create, add listeners and position component by code
    boxes.add(box);
    box.putClientProperty("seat", anSeatObject );
}

when required, in event listener, or during save phase this information can be read;

Additional note on the margin: personally I prefer table with SeatsByDate, not hundreds of column. In your model querying for free seats is almost impossible. Because I prefer JPA, I will make entity

@Enitity 
SeatsByDate {
  @Id
  int id;

  @ManyToOne
  ReserationDate date;

  bool isReserved;
}

and then

 SeatsByDate  anSeatObject 

So JPA is my personal preference, ClientProperty may be simple string too.

Answer 2

List<JCheckBox> boxArray = new ArrayList<JCheckBox>();
boxArray.add(box1);
boxArray.add(box2);
//.....
for(int i = 0;i<boxArray.size();i++){
  JCheckBox box = boxArray.get(i);
  String indexStr = i + 1;
  if(box.isSelected()){
      System.out.println("Hello");
      String query = "update booking set s" + indexStr+"= 0 where bdate ='"+d+"'";
      stmt.executeUpdate(query);
   }
}

Answer 3

Make use of loop statements and functions to achieve that. You could use FOR statement in a case where you know how many repetitions you need.

https://en.wikipedia.org/wiki/Control_flow#Loops

Assuming you have an array or collections with all the seats, you could make a function to update a specific seat passed as an argument and call it as many times you want within the FOR statement. It would be something like this:

public void updateBooking(Seat seat) {
    // You'd need to add here some stuff like db connection
    if (seat.isSelected()){
        System.out.println("Hello");
        String query = "update booking set " + seat.getId() + " = 0 where bdate ='" + d + "';";
        stmt.executeUpdate(query);
    }
}